A sunroof is a popular accessory item for a motor vehicle. The sunroof typically includes a closure panel that is movable relative to an opening formed through a roof of the vehicle. The closure panel is movable between a closed position generally flush with the roof that completely covers the opening, and an open position rearward of the closed position for allowing ventilation and/or sunlight to enter a passenger compartment of the vehicle. In addition, the closure panel is typically positionable at one of a plurality of partially open positions between the closed and open positions. The closure panel, which may be moved manually or via an electric motor, is retracted into the structure of the roof when open, where it is hidden from view.
Many sunroof assemblies have a shortcoming wherein noise is transmitted into the vehicle passenger compartment when the closure panel is in an open position, due to the flow of air proximate the sunroof opening. One component of the wind noise, commonly termed “buffeting” or “wind throb,” results from air rushing over an opening in a cavity and is generally characterized by relatively low-frequency noise. Another component of wind noise typically results from air rushing by or into obstructions at higher vehicle speeds and is generally characterized by high-frequency noise.
In an effort to attenuate the low frequency portion of the wind noise, wind deflectors have frequently been incorporated into sunroof assemblies. These wind deflectors may be fixed, or may pivot from a retracted position when the sunroof closure panel is closed to an extended position when the sunroof closure panel is opened. While fixed wind deflectors have been employed with some success, there is an inherent tradeoff in configuring a wind deflector to be effective in attenuating low-frequency noise while not generating high-frequency noise. For example, although the wind deflector can be configured to deflect the air beyond the sunroof opening to decrease wind throb, at higher vehicle speeds the deflector itself can generate high-frequency wind noise.
Pivotable wind deflectors that are manually or automatically adjustable are more effective to attenuate low- and high-frequency wind noise. Examples of such wind deflectors may be seen by reference to U.S. Pat. Nos. 6,523,889 and 6,174,025. However, such mechanical systems are complex, thereby increasing their cost and reducing their overall reliability. There is a need for a wind deflector that is effective to attenuate low- and high-frequency wind noise without resorting to complex mechanical systems.